1. Field of the Invention
This invention generally relates to the brewing of beverages. More specifically this invention relates to the construction and manufacture of sealed capsules containing infusible material, such as ground coffee, for brewing beverages.
2. Description of Related Art
For many years preparing a beverage, such as coffee, has involved brewing multiple servings in a pot or other container using loose coffee grounds. In some apparatus, the coffee grounds mix with hot water and are then removed from the brewed beverage as, for example, in the so-called “French press” coffee maker. Other apparatus directs hot liquid at low pressure through an open or closed basket containing the loosely ground coffee over a filter, such as a paper filter cone.
The procedures and apparatus for brewing beverages, particularly coffee, have undergone many transformations in recent years spurred by different market requirements. A convenience requirement led to prepackaged packets of ground coffee as a substitute for manually measuring coffee from bulk packages of loose, ground coffee, as in conventional drip coffee makers. A prepackaged packet comprises a permeable filter paper pouch with a pre-measured portion of loose ground coffee. An impervious package stores the packet to maintain freshness. A packet is removed from its package and placed in a basket or like receptacle. Then hot water at atmospheric pressure flows through the packet and its contents for extracting flavor and aroma from the ground coffee.
Another market requirement has evolved as many users have indicated a preference to brew individual beverage servings. This preference for single-serve coffee brewing apparatus, especially for home use, led to the development of pre-packaged disposable coffee capsules, or cartridges, and related brewing apparatus. For example, U.S. Pat. No. 4,921,712 to Malmquist discloses a disposable cartridge for use in an automatic drip-type beverage brewing machine. The cartridge comprises a first cup which has an open first end and a substantially closed second end penetrated by at least one port. A filter member contains ground coffee and nests within the first cup. A second cup has an open bottom end and a substantially closed top end and overlies the first cup. The closed end of the second cup has a plurality of holes and forms a shallow receptacle. A user removes a sealing foil from the second cup and places the cartridge on ledges in a brewing apparatus spaced from a water delivery spout. The apparatus delivers hot water at low pressure and at a controlled rate onto the top of the cartridge. There is no requirement for sealing between the apparatus and the cartridge so long as water does not overflow the shallow receptacle.
U.S. Pat. No. 7,097,074 (2006) and U.S. Patent Application No. 2004/01997444 both to Haliday et al. and U.S. Pat. No. 6,681,960 (2004) to Garman disclose another low-pressure beverage preparation system. In this system a brewing chamber receives a cartridge.
Minimizing the brewing time became another market requirement. It was determined early on that the extraction time or “brewing cycle” of such brewing apparatus could be shortened significantly if coffee beans were ground more finely than those used in such drip-type brewing apparatus. Finer grinding exposes a larger surface area to the water. However, the coffee grounds have a higher packing fraction and volumetric density. This increases hydraulic resistance to the flow of water through the cartridge and the grounds therein. Therefore, the water has to be delivered in a closed brewing chamber under an elevated pressure to be able to flow through the coffee in a short period of time.
This led to a development of sealed brewing chambers formed by members that are integral to the brewing apparatus. For example, U.S. Pat. No. 4,389,925 (1983) to Paina describes a beverage extracting and dispensing machine for use with flattened round cartridges. A cartridge contains a brewable product, such as ground coffee, and has permeable upper and lower walls traversing a substantially cylindrical side wall. In this reference a pressure plate coacts with the cartridge to provide sealing.
However, brewing under pressure creates a problem because seals about a brewing chamber are subject to leaking. One approach has been to design brewing chambers with intricate seals. However, as the seals become more important to the integrity of the process, the placement of capsules becomes more critical to prevent water from bypassing the capsule and to avoid interference between portions of the capsule and the brewing chamber that could cause the seal to leak.
Ease of cleaning has become yet another market requirement. Cleaning such brewing apparatus can be complicated and can introduce complexities in the design and manufacture of such apparatus. A sealed brewing chamber is a part of the brewing apparatus and its surfaces contact the brewed beverage. Thus, after use, it is necessary to clean the interior surfaces of the brewing chamber. Preferably such surfaces should be on components of the apparatus that are easily removed for cleaning.
Use of such brewing apparatus in a non-residential or non-home environment, such as in a hotel room or other commercial environment, imposes still other market requirements. Criteria for this commercial market are quite different. In a hotel environment, for example, in-room coffee apparatus must be inexpensive, be operated reliably with minimal operating costs and be easy to use. Moreover, and most importantly, such brewers must minimize the efforts of room attendants to clean and maintain the brewing apparatus, to dispose of used coffee grounds and to replenish coffee supplies in the room. In many hotels, in-room coffee apparatus includes a water heater, cups and prepackaged, pre-measured sealed packets of instant coffee. Other hotels have begun to use conventional coffee brewing machines that use capsules or cartridges to brew the coffee.
The advent of a desire to use a single apparatus to brew different serving sizes imposed another market requirement. When single-serve coffee brewing apparatus was introduced, there was a de facto standard serving size of about 175 ml (6 oz.). Over time, however, different single-serving sizes have become popular, requiring pre-measured packages of coffee in different sizes. One approach is to supply each pre-measured quantity in a cartridge of a unique size and capacity. A requirement for capsules of different sizes requires the capsule manufacturer to inventory parts for each size and adjust various parameters of the manufacturing process to accommodate such sizes. Moreover, differently sized capsules can complicate the construction of brewing apparatus to allow the apparatus to accommodate capsules of different sizes.
All of these market requirements have led to proposals for a wide variety of capsule structures and related apparatus. For example, U.S. Pat. Nos. 5,197,374, 5,242,702 and 5,897,899 (199) to Fond disclose devices for extracting coffee contained in a cartridge and a number of variations on sealed cartridges. The cartridge has a cup and cover to form a sealed container for an infusible material. When installed in a brewing apparatus, a water injector pierces either the cover or the cap to apply water under pressure to be discharged through a flow grill or like portion of the capsule.
In U.S. Pat. No. 4,846,052 to Favre et al., a device extracts material, such as coffee, from an infusible material contained in a sealed cartridge by puncturing one end of a cartridge with a sharpened water delivery tube and by perforating the other end of the cartridge to dispose the brewed beverage into a dispensing passage.
U.S. Pat. No. 5,794,519 (1998) to Fischer discloses a brewing head including lower and upper parts hingably connected together. A plurality of hollow needles project from the upper part into a brewing cavity for delivering water to the interior of a coffee brewing capsule. The lower part has projections intended to puncture the lower side of the coffee capsule. An ejector device within the upper part ejects a used coffee capsule.
U.S. Pat. No. 6,499,388 (2002) and U.S. Pat. No. 6,536,332 (2003) to Schmed disclose perforator members located in a brew chamber perforating one end of a coffee cartridge for extracting brew from the cartridge. The brew chamber forms a sealed receptacle during brewing.
U.S. Pat. No. 6,880,454 (2005) to Kollep discloses perforator members located in a brew chamber. The perforator members pierce a capsule to deliver water for brewing coffee. U.S. Pat. No. 6,966,251 (2005) to Yoakim discloses an alternate embodiment in which perforator members located in the brew chamber perforate a coffee capsule.
U.S. Patent Application No. 2005/0172822 to Macchi et al. discloses a cartridge for coffee. The cartridge comprises a container for a soluble product, a lid placed on top of the container and a filter positioned inside the container. A bottom wall of the container comprises a thin, weakened central portion and a breakable portion. The brewing apparatus receives the cartridge in a sealed chamber. After brewing, the pressure breaks the bottom to allow the beverage to be dispersed.
U.S. Pat. No. 6,607,762 (2003) to Lazaris et al. discloses a filter cartridge where a permeable beverage filter element divides the interior of the container into first and second chambers. Ribs support the permeable filter within the container. The first chamber contains the beverage medium; the second collects the brewed beverage for dispensing. Infusion and exit probes penetrate a lid to direct water into and brewed beverage from the first and second chambers, respectively.
U.S. Pat. No. 6,832,542 to Hu et al. discloses a capsule for preparation of beverages by directing hot water under pressure to the capsule. A section of the capsule is adapted to deform inwardly upon action of the internal water pressure. The capsule is in a sealed chamber during brewing.
U.S. Patent Application Nos. 2003/0172813, 2005/0150390 and 2005/0150391 to Schifferle disclose cartridges containing a single serving of substance extractable by means of water for preparing a beverage. Fluid director members positioned ahead of and behind the substance distribute the water. A gas-tight foil covers the cartridge. Specifically, U.S. Patent Application No. 2005/0150391 discloses a coffee maker for brewing powder coffee contained in a cartridge. The bottom of the cartridge is provided with an aperture. A foil covers the inside of the bottom of the cartridge.
Experience with prior art capsules and brewing apparatus have led to a new set of required market features for apparatus that can be used in both residential and commercial environments. Specifically these markets demand a capsule containing infusible material such as coffee, which is simple to use and inexpensive to manufacture and which preserves the freshness of the infusible material. The capsules must enable infusible material to be brewed under pressure in the capsule. The capsules must be tamper-proof so an individual user can be assured that others have not touched the capsule contents. When such capsules are used in a brewing apparatus, the brewing capsules must be sufficiently rigid for being stored in and dispensed from vending machines or other dispensers for preventing damage during brewing. They must also be readily disposable. Further, the capsule structure must enable the construction of a brewing apparatus that is easy to use and requires minimal maintenance. A review of the prior art described above demonstrates that each different capsule version may meet one or more of the requirements, but not all of them.
What is needed is a capsule that meets all the market requirements, that is easy and inexpensive to manufacture, is easy to use and enables the construction of brewing apparatus that meets all the market requirements for such apparatus and that requires minimal user maintenance.